In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists ...In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.展开更多
Currently, air pollution in Beijing has become a complex problem with two types of source pollutants： coal smoke and photochemical smog. Furthermore the maximum hourly mean concentration of O3 increases continuously,...Currently, air pollution in Beijing has become a complex problem with two types of source pollutants： coal smoke and photochemical smog. Furthermore the maximum hourly mean concentration of O3 increases continuously, especially in the summer. In order to simulate the photochemical reaction, develop an air quality simulation model and further improve the air quality of Beijing, a precisely temperature-controlled, indoor, smog chamber facility was designed and constructed at Tsinghua University. Characterization experiments have been carried out to acquire the basic parameters of the smog chamber, such as the wall loss rates of NO2, NO, O3, C3H6 and particulate matter （PM）, the intensity of ultraviolet （UV） light in the chamber, the reactivity of the purified air and the reproducibility of the experimental results. The results indicate that the facility performs up to specifications, and can meet the demands required for simulating the photochemical reaction. The effect of high primary contaminated PM on the formation of ozone and secondary organic aerosol （SOA） is under investigation.展开更多
Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied conditions.This study describes the construction and characterization of a new smog chamber facility for studying...Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied conditions.This study describes the construction and characterization of a new smog chamber facility for studying the formation mechanisms of gas-phase products and secondary organic aerosol from the photooxidation of volatile organic compounds.The chamber is a 5.4 m^(3) Fluorinated Ethylene Propylene(FEP)Teflon reactor with the potential to perform photooxidation experiments at controlled temperature and relative humidity.Detailed characterizations were conducted for evaluation of stability of environmental parameters,mixing time,background contamination,light intensity,and wall losses of gases and particles.The photolysis rate of NO_(2)(J_(NO2))ranged from(1.02-3.32)×10^(-3)sec^(-1),comparable to the average J_(NO2)in ambient environment.The wall loss rates for NO,NO_(2),and O_(3)were 0.47×10^(-4),0.37×10^(-4),and 1.17×10^(-4)min^(-1),while wall loss of toluene was obsoletely found in a 6 hr test.The particle number wall loss rates are(0.01-2.46)×10^(-3)min^(-1)for 40-350 nm with an average lifetime of more than one day.A series of toluene photooxidation experiments were carried out in absence of NO_xunder dry conditions.The results of the simulation experiments demonstrated that the chamber is well designed to simulate photolysis progress in the atmosphere.展开更多
The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and hum...The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.展开更多
Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result...Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result in deteriorating local air quality.In this study,a dynamic smog chamber was used to investigate the real-time emissions of gaseous and particulate pollutants during the combustion process and a static smog chamber was used to investigate the fume evolution under simulate light irradiation.The real-time emissions revealed that the total hydrocarbon （THC） and CO increased sharply after ignition,and then quickly decreased,indicating volatilization of hydrocarbons with low molecular weight and incomplete combustion at the beginning stage of combustion made great contribution to these pollutants.There was evident shoulder peak around 10min combustion for both THC and CO,revealing the emissions from vitrinite combustion.Additionally,another broad emission peak of CO after 30min was also observed,which was ascribed to the incomplete combustion of the inertinite.Compared with THC and CO,there was only one emission peak for NOx,SO 2 and particular matters at the beginning stage of combustion.The fume evolution with static chamber simulation indicated that evident consumption of SO 2 and NOx as well as new particle formation were observed.The consumption rates for SO 2 and NOx were about 3.44% hr-1 and 3.68% hr-1,the new particle formation of nuclei particles grew at a rate of 16.03 nm/hr during the first reaction hour,and the increase of the diameter of accumulation mode particles was evident.The addition of isoprene to the diluted mixture of the fume could promote O 3 and secondary particle formation.展开更多
Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber ...Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences(the CRAES Chamber),which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment.The chamber consisted of a 56-m^(3) fluorinated ethylene propylene(FEP) Teflon film reactor,an electrically-driven stainless steel alloy shield,an auxiliary system,and multiple detection instrumentations.By performing a series of characterization experiments,we obtained basic parameters of the CRAES chamber,such as the mixing ability,the background reactivity,and the wall loss rates of gaseous compounds(propene,NO,NO_(2),ozone) and aerosols(ammonium sulfate).Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol(SOA),including α-pinene ozonolysis,propene and 1,3,5-trimethylbenzene photooxidation.Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work:higher temperature and the presence of seed could reduce the vapor wall loss;SOA yield was found to depend inversely on temperature,and the presence of seed could increase SOA yield.The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls.The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.展开更多
The ozone formation reactivity of ethanol has been studied using chamber experiments and model simulations. The computer simulations are based on the MCM v3.1 mechanism with chamber-dependent auxiliary reactions. Resu...The ozone formation reactivity of ethanol has been studied using chamber experiments and model simulations. The computer simulations are based on the MCM v3.1 mechanism with chamber-dependent auxiliary reactions. Results show that the MCM mechanism can well simulate C 2 H 5 OH-NO x chamber experiments in our experimental conditions, especially on ozone formation. C 2 H 5 OH-NO x irradiations are less sensitive to relative humidity than alkane species under our experimental conditions. In order to well simulate the experiments under high relative humidity conditions, inclusion of N 2 O 5 +H 2 O=2HNO 3 in the MCM mechanism is necessary. Under C 2 H 5 OH-limited conditions, the C 2 H 5 OH/NO x ratio shows a positive effect on d(O 3 -NO)/dt and RO 2 +HO 2 . High C 2 H 5 OH/NO x ratios enhance the production of organoperoxide radical and HO 2 radical concentrations, which leads to a much quicker accumulation of ozone. By using ozone isopleths under typical scenarios conditions, the actual ozone formation ability of ethanol is predicted to be 2.3-3.5 part per billion (ppb) in normal cities, 3.5-146 ppb in cities where ethanol gas are widely used, and 0.2-3.2 ppb in remote areas. And maximum ozone formation potential from ethanol is predicted to be 4.0-5.8 ppb in normal cities, 5.8-305 ppb in cities using ethanol gas, and 0.2-3.8 ppb in remote areas.展开更多
A series of experiments were conducted in a self-made smog chamber at （300 ＋ 1） K and 1.01 × 10^5 Pa to simulate the photochemical reaction of ethyl methyl sulfide （EMS） and NOx. The results showed that the ...A series of experiments were conducted in a self-made smog chamber at （300 ＋ 1） K and 1.01 × 10^5 Pa to simulate the photochemical reaction of ethyl methyl sulfide （EMS） and NOx. The results showed that the higher the initial concentration of EMS, the more ozone was generated in the simulative reactions. It was found that the light intensity plays a very important role in the evaluation of ozone formation potential for EMS. The parameters of d（Oa-NO） and IR （incremental reactivity） were used to quantify the potential of EMS on ozone formation. The obtained maximum IR values in this article for the five simulative reactions were 1.55 × 10^-2, 0.99 × 10^-2, 1.36 × 10^-2, 2.47 × 10^-2, and 1.65 × 10^-2, respectively. A comparison between the results we obtained here and the results we obtained previously for di-tert-butyl peroxide and acetylene showed that the potential reactivity of EMS on ozone formation was at a relatively low level.展开更多
The composition of products formed from photooxidation of the aromatic hydrocarbon toluene was investigated. The OH-initiated photooxidation experiments were conducted by irradiating toluene/CH3ONO/NO/air mixtures in ...The composition of products formed from photooxidation of the aromatic hydrocarbon toluene was investigated. The OH-initiated photooxidation experiments were conducted by irradiating toluene/CH3ONO/NO/air mixtures in a smog chamber, the gaseous products were detected under the supersonic beam conditions by utilizing vacuum ultraviolet photoionization mass spectrometer using synchrotron radiation in real-time. And an aerosol time-of-flight mass spectrometer was used to provide on-line measurements of the individual secondary organic aerosol particle resulting from irradiating toluene. The experimental results demonstrated that there were some differences between the gaseous products and that of particle-phase, the products of glyoxal, 2-hydroxyl-3-oxo-butanal, nitrotoluene, and methyl-nitrophenol only existed in the particle-phase. However, furane, methylglyoxal, 2-methylfurane, benzaldehyde, cresol, and benzoic acid were the predominant photooxidation products in both the gas phase and particle phase.展开更多
基金This work was supported by the Natural Science Foundation of Anhui Province, China （No.1208085MD59）, the National Natural Science Foundation of China （No.U1232209, No.41175121, and No.21307137）, the Presidential Foundation of Hefei Institutes of Physical Science, Chinese Academy of Sciences, China （No.YZJJ201302）, and the Knowledge Innovation Foundation of the Chinese Academy of Sciences （No.KJCX2-YW-N24）.
文摘In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol （SOA）, an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ～830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere.
文摘Currently, air pollution in Beijing has become a complex problem with two types of source pollutants： coal smoke and photochemical smog. Furthermore the maximum hourly mean concentration of O3 increases continuously, especially in the summer. In order to simulate the photochemical reaction, develop an air quality simulation model and further improve the air quality of Beijing, a precisely temperature-controlled, indoor, smog chamber facility was designed and constructed at Tsinghua University. Characterization experiments have been carried out to acquire the basic parameters of the smog chamber, such as the wall loss rates of NO2, NO, O3, C3H6 and particulate matter （PM）, the intensity of ultraviolet （UV） light in the chamber, the reactivity of the purified air and the reproducibility of the experimental results. The results indicate that the facility performs up to specifications, and can meet the demands required for simulating the photochemical reaction. The effect of high primary contaminated PM on the formation of ozone and secondary organic aerosol （SOA） is under investigation.
基金financially supported by the Research Grants Council (RGC)of Hong Kong Special Administrative Region,China (No.T24-504/17-N)。
文摘Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied conditions.This study describes the construction and characterization of a new smog chamber facility for studying the formation mechanisms of gas-phase products and secondary organic aerosol from the photooxidation of volatile organic compounds.The chamber is a 5.4 m^(3) Fluorinated Ethylene Propylene(FEP)Teflon reactor with the potential to perform photooxidation experiments at controlled temperature and relative humidity.Detailed characterizations were conducted for evaluation of stability of environmental parameters,mixing time,background contamination,light intensity,and wall losses of gases and particles.The photolysis rate of NO_(2)(J_(NO2))ranged from(1.02-3.32)×10^(-3)sec^(-1),comparable to the average J_(NO2)in ambient environment.The wall loss rates for NO,NO_(2),and O_(3)were 0.47×10^(-4),0.37×10^(-4),and 1.17×10^(-4)min^(-1),while wall loss of toluene was obsoletely found in a 6 hr test.The particle number wall loss rates are(0.01-2.46)×10^(-3)min^(-1)for 40-350 nm with an average lifetime of more than one day.A series of toluene photooxidation experiments were carried out in absence of NO_xunder dry conditions.The results of the simulation experiments demonstrated that the chamber is well designed to simulate photolysis progress in the atmosphere.
基金supported by the Central Level,Scientific Research Institutes for Basic R&D Special Fund Business,China(No.2021-JY-16)the National Natural Science Foundation of China(Nos.42075182 and 2130721)+1 种基金the National Research Program for Key Issue in Air Pollution Control(No.DQGG2021101)the National Key Research and Development Program of China(No.2019YFC0214800)。
文摘The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.
基金supported by the Central Public-Interest Scientific Institution Basal Research Fund (No. 2009KYYW01)the National Natural Science Foundation of China (No. 40705043)the Open Foundation of Environmental Simulation and Pollution Control State Key Laboratories (Peking University)
文摘Domestic coal stoves are widely used in countryside and greenbelt residents in China for heating and cooking,and emit considerable pollutants to the atmosphere because of no treatment of their exhaust,which can result in deteriorating local air quality.In this study,a dynamic smog chamber was used to investigate the real-time emissions of gaseous and particulate pollutants during the combustion process and a static smog chamber was used to investigate the fume evolution under simulate light irradiation.The real-time emissions revealed that the total hydrocarbon （THC） and CO increased sharply after ignition,and then quickly decreased,indicating volatilization of hydrocarbons with low molecular weight and incomplete combustion at the beginning stage of combustion made great contribution to these pollutants.There was evident shoulder peak around 10min combustion for both THC and CO,revealing the emissions from vitrinite combustion.Additionally,another broad emission peak of CO after 30min was also observed,which was ascribed to the incomplete combustion of the inertinite.Compared with THC and CO,there was only one emission peak for NOx,SO 2 and particular matters at the beginning stage of combustion.The fume evolution with static chamber simulation indicated that evident consumption of SO 2 and NOx as well as new particle formation were observed.The consumption rates for SO 2 and NOx were about 3.44% hr-1 and 3.68% hr-1,the new particle formation of nuclei particles grew at a rate of 16.03 nm/hr during the first reaction hour,and the increase of the diameter of accumulation mode particles was evident.The addition of isoprene to the diluted mixture of the fume could promote O 3 and secondary particle formation.
基金supported by the China Postdoctoral Science Foundation (No.2019M660752)the Beijing Municipal Science&Technology Commission (No.Z181100005418015),LAC/CMA (No.2019B08)+2 种基金the Fundamental Research Funds for Central Public Welfare Scientific Research Institutes of ChinaChinese Research Academy of Environmental Sciences (Nos.GYG5051201,2009GGQD18,2019YSKY-018,2019YSKY-012)the Chinese Academy of Sciences Strategic Leading Science and Technology Project (Class B)(No.XDB05010200)。
文摘Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences(the CRAES Chamber),which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment.The chamber consisted of a 56-m^(3) fluorinated ethylene propylene(FEP) Teflon film reactor,an electrically-driven stainless steel alloy shield,an auxiliary system,and multiple detection instrumentations.By performing a series of characterization experiments,we obtained basic parameters of the CRAES chamber,such as the mixing ability,the background reactivity,and the wall loss rates of gaseous compounds(propene,NO,NO_(2),ozone) and aerosols(ammonium sulfate).Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol(SOA),including α-pinene ozonolysis,propene and 1,3,5-trimethylbenzene photooxidation.Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work:higher temperature and the presence of seed could reduce the vapor wall loss;SOA yield was found to depend inversely on temperature,and the presence of seed could increase SOA yield.The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls.The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q02-03)the National Natural Science Foundation of China (41105086)
文摘The ozone formation reactivity of ethanol has been studied using chamber experiments and model simulations. The computer simulations are based on the MCM v3.1 mechanism with chamber-dependent auxiliary reactions. Results show that the MCM mechanism can well simulate C 2 H 5 OH-NO x chamber experiments in our experimental conditions, especially on ozone formation. C 2 H 5 OH-NO x irradiations are less sensitive to relative humidity than alkane species under our experimental conditions. In order to well simulate the experiments under high relative humidity conditions, inclusion of N 2 O 5 +H 2 O=2HNO 3 in the MCM mechanism is necessary. Under C 2 H 5 OH-limited conditions, the C 2 H 5 OH/NO x ratio shows a positive effect on d(O 3 -NO)/dt and RO 2 +HO 2 . High C 2 H 5 OH/NO x ratios enhance the production of organoperoxide radical and HO 2 radical concentrations, which leads to a much quicker accumulation of ozone. By using ozone isopleths under typical scenarios conditions, the actual ozone formation ability of ethanol is predicted to be 2.3-3.5 part per billion (ppb) in normal cities, 3.5-146 ppb in cities where ethanol gas are widely used, and 0.2-3.2 ppb in remote areas. And maximum ozone formation potential from ethanol is predicted to be 4.0-5.8 ppb in normal cities, 5.8-305 ppb in cities using ethanol gas, and 0.2-3.8 ppb in remote areas.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No. KZCX2-YW-205)the National Natural Sci-ence Foundation of China (No. 20577052, 20673123,20503035).
文摘A series of experiments were conducted in a self-made smog chamber at （300 ＋ 1） K and 1.01 × 10^5 Pa to simulate the photochemical reaction of ethyl methyl sulfide （EMS） and NOx. The results showed that the higher the initial concentration of EMS, the more ozone was generated in the simulative reactions. It was found that the light intensity plays a very important role in the evaluation of ozone formation potential for EMS. The parameters of d（Oa-NO） and IR （incremental reactivity） were used to quantify the potential of EMS on ozone formation. The obtained maximum IR values in this article for the five simulative reactions were 1.55 × 10^-2, 0.99 × 10^-2, 1.36 × 10^-2, 2.47 × 10^-2, and 1.65 × 10^-2, respectively. A comparison between the results we obtained here and the results we obtained previously for di-tert-butyl peroxide and acetylene showed that the potential reactivity of EMS on ozone formation was at a relatively low level.
基金This work was supported by the Open Research Fund of Key Laboratory of Atmospheric Composition and Optical Radiation, Chinese Academy of Sciences （No.J J-10-04）, Knowledge Innovation Foundation of Chinese Academy of Sciences （KJCX2-YW-N24）, and the National Natural Science Foundation of China （No.40975080 and No.10979061）.
文摘The composition of products formed from photooxidation of the aromatic hydrocarbon toluene was investigated. The OH-initiated photooxidation experiments were conducted by irradiating toluene/CH3ONO/NO/air mixtures in a smog chamber, the gaseous products were detected under the supersonic beam conditions by utilizing vacuum ultraviolet photoionization mass spectrometer using synchrotron radiation in real-time. And an aerosol time-of-flight mass spectrometer was used to provide on-line measurements of the individual secondary organic aerosol particle resulting from irradiating toluene. The experimental results demonstrated that there were some differences between the gaseous products and that of particle-phase, the products of glyoxal, 2-hydroxyl-3-oxo-butanal, nitrotoluene, and methyl-nitrophenol only existed in the particle-phase. However, furane, methylglyoxal, 2-methylfurane, benzaldehyde, cresol, and benzoic acid were the predominant photooxidation products in both the gas phase and particle phase.
基金supported by the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB05010400)National Key Basic Research Program of China(973)(2011CB403401)National Natural Science Foundation of China(21190052,41173112,41227805)~~
